This disclosure relates generally to the field of aircraft, and more particularly to a discrete input determining circuit and a discrete input determining method.
Avionics products often provide circuits to read, ascertain or otherwise determine discrete inputs from other equipment in the aircraft. The discrete inputs may conform, for example, to one of two types: OPEN/GND or 28V/OPEN. Avionics products have typically used two different circuits to accommodate the two discrete types, providing internal pullups for the OPEN/GND discrete input and internal pulldowns for 28V/OPEN discrete input. Therefore, the avionics products have frequently provided a quantity of each circuit type to cover a variety of possible aircraft applications. For any given application, rarely are all the discrete inputs of both types utilized, and often there is a shortage of one type or the other. This may result in valuable hardware being left unused, reducing the flexibility and cost-effectiveness of the product.